[FIX] account: fix _toggle_reconcile_to_false() on empty recordset

When the method _toggle_reconcile_to_false was called on an empty recordset (e.g existing account is imported with reconcile=False and the field was already False), an SQL error was raised.

Fixes #29326

closes odoo/odoo#29458

addons/account/models/account.py

@@ -290,6 +290,8 @@ class AccountAccount(models.Model):
 
         Note that it is disallowed if some lines are partially reconciled.
         '''
+        if not self.ids:
+            return None
         partial_lines_count = self.env['account.move.line'].search_count([
             ('account_id', 'in', self.ids),
             ('full_reconcile_id', '=', False),